O'Neill said: "I think that in terms of fitness the game on Tuesday will have brought Gareth on so, if he's mentally tuned in and he wants to go and play, why not?
"Why shouldn't he be in contention for the game? He's a quality player and that's what we're looking for."
He said: "Deep down we would all love him to stay at the football club. We haven't heard back from Liverpool for some time and we're not exactly sure where we all stand.
"When people say people are in limbo, I don't think that applies to anybody more than ourselves. We don't know whether to move forward or not with it.
"It's a long-running saga and I wouldn't mind it ending one way or another.
"My preference - and hopefully I'm speaking for a lot of Villa fans, if not all of them - is that we would like Gareth to stay at the football club.
"That would be great because it will be hard to replace him.
"But we're not sure where Liverpool stand now. It was never mentioned before about them needing to sell some players before they bought - that was never in the system at all. But seemingly it must be part of it.
"The point is that this has been long running and we're looking to see it end one way or another."